Super-radiant Smith-Purcell Radiation Excited by Multi-beam in Two-dimensional Periodic Columns

This paper proposes a structure composed of two-dimensional periodic columns to reduce the start current density of multi-beam which excites Super-radiant Smith-Purcell radiation. The dispersion of periodic columns is deduced by means of resonance method to predict the frequency of surface wave. The electromagnetic wave at the frequency is excited by the inverse wave oscillation mechanism and super-radiation is emitted at the harmonic of the frequency. Super-radiant Smith-Purcell radiation is simulated by a 3D particle-in-cell (pic) simulation and the super-radiation in periodic columns gets lower start current density (7.5 A/cm²) and higher output power (440 mW) compared with the super-radiation in flat grating. Accordingly, this method is expected to greatly improve the performance of miniaturized and tunable terahertz radiation sources.